diff --git a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.qhelp b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.qhelp
index 6ff60d383419..d9b5a0220773 100644
--- a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.qhelp	
+++ b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.qhelp	
@@ -14,6 +14,9 @@ function may behave unpredictably.</p>
 <p>This may indicate a misspelled function name, or that the required header containing
 the function declaration has not been included.</p>
 
+<p>Note: This query is not compatible with build mode: none databases, and produces
+no results on those databases.</p>
+
 </overview>
 <recommendation>
 <p>Provide an explicit declaration of the function before invoking it.</p>
@@ -26,4 +29,4 @@ the function declaration has not been included.</p>
 <references>
 <li>SEI CERT C Coding Standard: <a href="https://wiki.sei.cmu.edu/confluence/display/c/DCL31-C.+Declare+identifiers+before+using+them">DCL31-C. Declare identifiers before using them</a></li>
 </references>
-</qhelp>
\ No newline at end of file
+</qhelp>
diff --git a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql
index 6a55557cf70b..007ef71a1630 100644
--- a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql	
+++ b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql	
@@ -17,6 +17,11 @@ import TooFewArguments
 import TooManyArguments
 import semmle.code.cpp.commons.Exclusions
 
+/*
+ * This query is not compatible with build mode: none databases, and has
+ * no results on those databases.
+ */
+
 predicate locInfo(Locatable e, File file, int line, int col) {
   e.getFile() = file and
   e.getLocation().getStartLine() = line and
@@ -39,6 +44,7 @@ predicate isCompiledAsC(File f) {
 from FunctionDeclarationEntry fdeIm, FunctionCall fc
 where
   isCompiledAsC(fdeIm.getFile()) and
+  not any(Compilation c).buildModeNone() and
   not isFromMacroDefinition(fc) and
   fdeIm.isImplicit() and
   sameLocation(fdeIm, fc) and
diff --git a/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md b/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md
new file mode 100644
index 000000000000..8c2c431ec24c
--- /dev/null
+++ b/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md
@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* The "Implicit function declaration" (`cpp/implicit-function-declaration`) query no longer produces results on `build mode: none` databases. These results were found to be very noisy and fundamentally imprecise in this mode.