diff --git a/src/asm/lexer.cpp b/src/asm/lexer.cpp
index 0ddc42a0..46b20564 100644
--- a/src/asm/lexer.cpp
+++ b/src/asm/lexer.cpp
@@ -377,7 +377,7 @@ void lexer_IncIFDepth() {
 
 void lexer_DecIFDepth() {
 	if (lexerState->ifStack.empty())
-		fatalerror("Found ENDC outside an IF construct\n");
+		fatalerror("Found ENDC outside of an IF construct\n");
 
 	lexerState->ifStack.pop_front();
 }
diff --git a/src/asm/parser.y b/src/asm/parser.y
index f3d96124..510d9a4a 100644
--- a/src/asm/parser.y
+++ b/src/asm/parser.y
@@ -484,7 +484,7 @@ if:
 elif:
 	POP_ELIF const NEWLINE {
 		if (lexer_GetIFDepth() == 0)
-			fatalerror("Found ELIF outside an IF construct\n");
+			fatalerror("Found ELIF outside of an IF construct\n");
 
 		if (lexer_RanIFBlock()) {
 			if (lexer_ReachedELSEBlock())
@@ -502,7 +502,7 @@ elif:
 else:
 	POP_ELSE NEWLINE {
 		if (lexer_GetIFDepth() == 0)
-			fatalerror("Found ELSE outside an IF construct\n");
+			fatalerror("Found ELSE outside of an IF construct\n");
 
 		if (lexer_RanIFBlock()) {
 			if (lexer_ReachedELSEBlock())
diff --git a/src/asm/rpn.cpp b/src/asm/rpn.cpp
index 6d11b59c..a9296958 100644
--- a/src/asm/rpn.cpp
+++ b/src/asm/rpn.cpp
@@ -71,7 +71,7 @@ void Expression::makeNumber(uint32_t value) {
 void Expression::makeSymbol(std::string const &symName) {
 	clear();
 	if (Symbol *sym = sym_FindScopedSymbol(symName); sym_IsPC(sym) && !sect_GetSymbolSection()) {
-		error("PC has no value outside a section\n");
+		error("PC has no value outside of a section\n");
 		data = 0;
 	} else if (!sym || !sym->isConstant()) {
 		isSymbol = true;
@@ -98,7 +98,7 @@ void Expression::makeBankSymbol(std::string const &symName) {
 	if (Symbol const *sym = sym_FindScopedSymbol(symName); sym_IsPC(sym)) {
 		// The @ symbol is treated differently.
 		if (!currentSection) {
-			error("PC has no bank outside a section\n");
+			error("PC has no bank outside of a section\n");
 			data = 1;
 		} else if (currentSection->bank == (uint32_t)-1) {
 			data = "Current section's bank is not known";
diff --git a/src/asm/symbol.cpp b/src/asm/symbol.cpp
index 14ae47b7..b62fb5e8 100644
--- a/src/asm/symbol.cpp
+++ b/src/asm/symbol.cpp
@@ -45,7 +45,7 @@ static int32_t Callback_NARG() {
 	if (MacroArgs const *macroArgs = fstk_GetCurrentMacroArgs(); macroArgs) {
 		return macroArgs->nbArgs();
 	} else {
-		error("_NARG does not make sense outside of a macro\n");
+		error("_NARG has no value outside of a macro\n");
 		return 0;
 	}
 }
@@ -145,11 +145,11 @@ Symbol *sym_FindScopedSymbol(std::string const &symName) {
 Symbol *sym_FindScopedValidSymbol(std::string const &symName) {
 	Symbol *sym = sym_FindScopedSymbol(symName);
 
-	// `@` has no value outside a section
+	// `@` has no value outside of a section
 	if (sym_IsPC(sym) && !sect_GetSymbolSection()) {
 		return nullptr;
 	}
-	// `_NARG` has no value outside a macro
+	// `_NARG` has no value outside of a macro
 	if (sym == _NARGSymbol && !fstk_GetCurrentMacroArgs()) {
 		return nullptr;
 	}
@@ -205,9 +205,9 @@ uint32_t sym_GetPCValue() {
 	Section const *sect = sect_GetSymbolSection();
 
 	if (!sect)
-		error("PC has no value outside a section\n");
+		error("PC has no value outside of a section\n");
 	else if (sect->org == (uint32_t)-1)
-		error("Expected constant PC but section is not fixed\n");
+		error("PC does not have a constant value; the current section is not fixed\n");
 	else
 		return CallbackPC();
 	return 0;
diff --git a/src/link/patch.cpp b/src/link/patch.cpp
index 25d4de64..a3724519 100644
--- a/src/link/patch.cpp
+++ b/src/link/patch.cpp
@@ -267,7 +267,7 @@ static int32_t computeRPNExpr(Patch const &patch, std::vector<Symbol> const &fil
 
 		case RPN_BANK_SELF:
 			if (!patch.pcSection) {
-				error(patch.src, patch.lineNo, "PC has no bank outside a section");
+				error(patch.src, patch.lineNo, "PC has no bank outside of a section");
 				isError = true;
 				value = 1;
 			} else {
@@ -374,7 +374,7 @@ static int32_t computeRPNExpr(Patch const &patch, std::vector<Symbol> const &fil
 
 			if (value == -1) { // PC
 				if (!patch.pcSection) {
-					error(patch.src, patch.lineNo, "PC has no value outside a section");
+					error(patch.src, patch.lineNo, "PC has no value outside of a section");
 					value = 0;
 					isError = true;
 				} else {
diff --git a/test/asm/assert-nosect-bank.err b/test/asm/assert-nosect-bank.err
index dc428bf0..019bbd96 100644
--- a/test/asm/assert-nosect-bank.err
+++ b/test/asm/assert-nosect-bank.err
@@ -1,3 +1,3 @@
 error: assert-nosect-bank.asm(1):
-    PC has no bank outside a section
+    PC has no bank outside of a section
 error: Assembly aborted (1 error)!
diff --git a/test/asm/assert@-no-sect.err b/test/asm/assert@-no-sect.err
index 2032c41c..31bff018 100644
--- a/test/asm/assert@-no-sect.err
+++ b/test/asm/assert@-no-sect.err
@@ -1,3 +1,3 @@
 error: assert@-no-sect.asm(1):
-    PC has no value outside a section
+    PC has no value outside of a section
 error: Assembly aborted (1 error)!
diff --git a/test/asm/bracketed-symbols.err b/test/asm/bracketed-symbols.err
index 9fdd7091..81a0008c 100644
--- a/test/asm/bracketed-symbols.err
+++ b/test/asm/bracketed-symbols.err
@@ -3,5 +3,5 @@ error: bracketed-symbols.asm(16):
 error: bracketed-symbols.asm(20):
     "Label" does not have a constant value
 error: bracketed-symbols.asm(21):
-    Expected constant PC but section is not fixed
+    PC does not have a constant value; the current section is not fixed
 error: Assembly aborted (3 errors)!
diff --git a/test/asm/const-and.err b/test/asm/const-and.err
index 68e3894d..74abe12c 100644
--- a/test/asm/const-and.err
+++ b/test/asm/const-and.err
@@ -1,5 +1,5 @@
 error: const-and.asm(2):
-    PC has no value outside a section
+    PC has no value outside of a section
 error: const-and.asm(11):
     Expected constant expression: 'Aligned' is not constant at assembly time
 error: const-and.asm(17):
diff --git a/test/asm/endc-outside-if.err b/test/asm/endc-outside-if.err
index 274d8d6e..f2c1b96f 100644
--- a/test/asm/endc-outside-if.err
+++ b/test/asm/endc-outside-if.err
@@ -1,2 +1,2 @@
 FATAL: endc-outside-if.asm(1):
-    Found ENDC outside an IF construct
+    Found ENDC outside of an IF construct
diff --git a/test/asm/undefined-builtins.err b/test/asm/undefined-builtins.err
index a75ce6f7..219b4e0e 100644
--- a/test/asm/undefined-builtins.err
+++ b/test/asm/undefined-builtins.err
@@ -1,9 +1,9 @@
 error: undefined-builtins.asm(3):
-    PC has no value outside a section
+    PC has no value outside of a section
 error: undefined-builtins.asm(4):
     Interpolated symbol "@" does not exist
 error: undefined-builtins.asm(8):
-    _NARG does not make sense outside of a macro
+    _NARG has no value outside of a macro
 error: undefined-builtins.asm(9):
     Interpolated symbol "_NARG" does not exist
 error: Assembly aborted (4 errors)!